Electronic devices that consume a large amount of power often create heat that needs to be removed during operation. For this reason, many electronic devices include cooling fans. For example most computers and other computing devices include cooling fans. For some devices, it is important not only to cool the device in general, but to ensure each component of the device is adequately cooled. For example, devices having numerous of printed circuit boards spaced closely together leave small air gaps (slots) between the cards, and may require a certain amount of air to pass through each slot to keep the individual components on each card adequately cooled.
Cooling fans create turbulent airflow on the downstream side of the fan. In a device including a plurality of cards spaced closely together, the turbulent airflow often results in unequal flow rates through the slots formed between the cards. In order to assure adequate airflow through each slot, larger or more fans may be used in the device even though the total airflow is theoretically sufficient to cool each component of the device. One alternative is to use ducting to direct airflow to each slot. Another is to use baffles to limit airflow in slots that would otherwise receive more airflow than necessary in order to force the flow to other slots. Another possibility is a plenum pressure equalization chamber, which provides a large space for turbulent airflow to equalize into a consistent pressure across the chamber. The calm air and even pressure on the downstream side of the chamber means air exits equal sized outlets of the chamber at equal flow rates.
However, each of these techniques has disadvantages. Larger or extra fans take up additional space, are more expensive and consume excess power. Ducting or plenum pressure equalization chambers can take up even more space than having extra fans. Baffles increase the overall pressure in the system and may require use of larger or more fans than otherwise theoretically necessary. In other words, current techniques for directing airflow often result in electronic device designs resulting in an inefficient use of power, space and/or production resources.